This proposal is for the purchase the Perkin Elmer (PE) Opera Phenix Automated High-throughput, High- content Confocal/Wide-field Microscope for the QB3 Shared Stem Cell Facility/High-Throughput Screening Facility (SSCF/HTSF). High-content screening (HCS) encompasses a set of analytical methods using automated microscopy, multi-parameter image processing, and visualization tools to extract quantitative data from cell populations. HCS typically employs fluorescence imaging of samples in a high-throughput format and reports quantitatively on parameters such as spatial distribution of targets and individual cell and organelle morphology. This proposed instrument system will enable high-content screens and other multi-conditional experiments that demand confocal imaging as opposed to wide-field imaging for their proper analysis, thereby greatly advancing the research capabilities of our faculty. We present the research of 5 Major Users and 4 Minor Users whose primarily NIH-funded, biomedical research would be carried forward through use of this instrument. Research topics include basic biology, cancer biology, and stem cell research. On the UC Berkeley campus there is currently no other instrument of its kind, and Berkeley faculty conducting HCS research are currently unable to conduct many classes of screens because there is no current capacity for high throughput acquisition of confocal images, including for example on cellular samples in multiple multi- well plates. As a core facility instrument, the proposed automated confocal microscope is designed for flexibility and can address an array of imaging needs such as confocal, transmitted light, live-cell imaging, wide-field imaging, time-lapse, and Z-stacks for 3D reconstruction and analysis. This instrument has the speed and accuracy that many of today?s experiments demand. In the past four years, PI Dr. Mary West has engaged in demonstrations of different versions of automated confocal imagers from various vendors and compared their capabilities to potential user needs. The instruments tested included the General Electric InCell 6000, the Molecular Devices Ultra and most recently, the IXM Confocal, and the Perkin Elmer Operetta. The PE Opera Phenix uniquely meets the needs of the multiple users surveyed, excels in several key areas of its design such as resolution and speed, and offers the best price point for a complete state of the art, turn-key system. Housing Opera Phenix in the HTSF with its particular HTS liquid handling automation capabilities, and staff expertise in facilitating screening experiments and image analysis will ensure successful instrument installation, operation and management as well as maximum accessibility and use.